Fuente: Wipo "Sensorization" An inspection apparatus for inspecting horizontal tubes in an industrial environment includes a drive module including a pair of wheels to engage a top tube of a vertically arranged layer of tubes, a telescoping pole, a sensor carriage assembly coupled to the telescoping pole, a lowering mechanism operationally coupled to the telescoping pole to selectively extend or retract the telescoping pole providing a selected vertical position of the sensor carriage assembly, and an encoder including a passive wheel, a spring, and a sliding coupler. The spring biases the passive wheel toward the top tube to ensure contact between the passive wheel and a surface of the top tube.